What is there to know? There are sort of bicycles with engines. Inhabit a nether world between autos and bicycles. Come in at least as great a variety of styles as autos. They have controls that you have to learn to use, just like a car. If you know how to ride a bicycle, or once did, learning will be easier. Given a large empty parking lot, I can teach you to operate one in 20 minutes. Learning to proficiently operate the controls takes about
10-40 hours. Learning to operate a motorcycle safely in traffic is something that you never stop learning. Motorcycles are relatively dangerous machines. Protective clothing can help a lot. Riding style is a big factor too. You can buy insanely powerful motorcycles for less than the cost of an average motorcycle. You can buy a motorcycle quite similar to professional racing bikes for 10 grand, give or take. (You can't touch a Nascar or Indy car for anything close to the price of an typical car.) Motorcycles can be fun to drive. Ones with small engines can get 2 or 3 or 4 times the miles per gallon of a car. Big ones can drop to around 30 mpg. Bikes cost from $2,500 to $25,000. Learning to ride on a small bike is easier, and safer. There are 4 kinds of bikes, although the lines blur: crotch rockets, cruisers, off road bikes, and standards (which is what all bikes were before ~1975.) Motorcycles can have 1, 2, 3, or 4 cylinders. Air cooled or water cooled. Most Jap bikes are pretty reliable. The dependability of American bikes (primarily Harley) is debated, but the modern ones are pretty reliable. European bikes are like European cars. Go to a dealer, sit on some bikes, go to he library and read Cycle World or a similar mag.What else is there to know?